A scanner system for scanning targets such as bar codes detect the light reflected back from the bar code and process the reflected light signal to determine the time position of the black to white and the white to black transitions between the symbols of the bar code. The signal strength of the reflected light signal will vary across the field of view (FOV) of the scanner system due to the geometry of the scanner mechanism, positioning of the bar code, receiving system gain versus angle, and ambient light intensity. Generally, the scanner system should maximize the sensitivity of the scanner system while still rejecting high levels of noise. To achieve this, typical scanner systems utilize zero crossings of the second derivative of the reflected signal to detect black to white and white to black transitions. However, using a second derivative of the reflected signal is computationally complex and therefore involves more circuitry or processing power.
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